Research Article
Kasaye T, Melese A, Amare G
Abstract
Cassava and yam are a source of food security, not only because it can be grown on less productive land, butbecause it is a source of income for producers and generally a low cost source of food. Hence, the present tuberswere cultivated new region of Ethiopia which is not cultivated yet. This work aims at examining the physical,chemical and functional properties of flour produced from cassava and yam tubers collected from Shewa Robitintegrated research and development site of Debre Berhan University, North Shewa Administrative Zone,Shewarobit, Ethiopia. The flours were produced using fermentation and boiling processing methods. Floursproduces were subjected to physio-chemical and functional properties analyses. The tubers were washed, sorted,peeled and sliced. The sliced tubers were divided into two portions. One portion was fermented for 72 hr. The otherportion was boiled for about 45 minutes. Both prepared samples were dried using sun. The moisture contents of thesamples were 9.51% for cassava and 12.46% for yam for raw samples. Based on dry weight basis, the ash, crudefat, protein and crude fiber were 2.47, 1.12, 1.02 and 4.09%, respectively, for the raw sample of cassava and 3.81,0.69, 6.98, and 3.77% for the raw sample of yam. The mineral contents of the samples were 734.88, 639.71 mg/kgCa, 30.38, 51.52 mg/kg Fe, and 4.7, 15.93 mg/kg Zn content in raw cassava and yam samples, respectively. Amongthe anti-nutritional factors analyzed, the level of cyanide, phytate and oxalate were determined to be 36.2, 809.48and 2.32 mg/1000 g in raw cassava sample respectively and the level of tannin and oxalate 1036.0 and 14.03 mg/kgin raw yam sample respectively. Both cyanide and phytate were not detected in raw yam samples and also in rawcassava tannin is not detected. A reduction of 98.23%, 37.4% and 4.31% in the level of cyanide, phytate, andoxalate was achieved by boiling process respectively and fermentation brought about 100%, 48.5% and 31.9%, inthe level of cyanide, phytate and oxalates in cassava samples. Tannin and oxalate were reduced by 69.2% and30.8% by boiling and 70.7% and 69.13% reduction was achieved by fermentation for yam samples. The bulkdensity, water absorption capacity, oil absorption capacity, foaming capacity and foam stability were within the rangeof 0.65-0.86 g/ml, 0.65-0.86 ml/g, 0.8-1.24 ml/g, 2.55-3.25% and 2.25-2.56% for cassava flour and 0.64-0.97 g/ml,0.64 to 1.12 ml/g, 0.55-0.87 ml/g, 3.26-3.56% and 0.87-2.45% for yam flour samples, respectively. Naturalfermentation has resulted in reduction in all types of anti-nutrients for both cassava and yam samples, particularly,cyanide. Fermented cassava and yam flours will have a good potential for product development.